Episodic migraine is a debilitating chronic pain condition afflicting 12% of American adults. Current conventional treatments rely on medications that provide limited or transient relief, target symptoms rather than the underlying causes of pain, and are associated with significant side effects and costs. It is therefore essential to investigate non-pharmacologic approaches to conventional headache treatments. Omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFAs) regulate multiple pain-related biochemical pathways. Controlled clinical trials investigating pain modulation in response to dietary changes while exploring relevant mechanisms of action in humans are lacking. In a recent feasibility study in patients with chronic daily headache (CDH), we found that targeted PUFA modifications - increased dietary n-3 EPA+DHA with reduced n-6 linoleic acid (LA) intake - altered circulating endovanilloids, while reducing headache frequency and improving quality of life. These findings support our proposed model in which diet-induced alterations in endovanilloids modulate TRPV1 activity in vivo, leading to important implications for migraine and chronic pain in general. However, whether a reduction in dietary LA is required to elicit the observed metabolic and clinical benefits of raising n-3 PUFA intake is unknown. The goal of this research is to assess whether dietary PUFA modifications designed to increase tissue n-3 EPA and DHA, with or without concurrent reduction in n-6 LA, can result in predicted changes in circulating endovanilloids and improvement in headache-related clinical outcomes. The proposed 3-arm, 20-week, randomized, controlled, single-blind trial, with 51 subjects in each group, includes a 4-week baseline of usual care, followed by randomization to one of three 16-week dietary interventions plus usual care: 1) a High n-3 EPA+DHA, Low n-6 LA intervention (Diet A); 2) a High n-3 EPA+DHA, High n-6 LA intervention (Diet B); or 3) a control intervention with average U.S. intakes (Low n-3, High n-6, Diet C). Specific aims are: 1) To assess the efficacy of the dietary interventions in inducing the predicted changes in circulating PUFA endovanilloid derivatives; 2) To compare the clinical effects in migraine specific outcomes of two 16-week analgesic dietary interventions with each other and a control diet; 3) To test, in an exploratory manner, our model of the proposed causal chain linking changes in n-3 and n-6 PUFAs, their endovanilloid derivatives, and headache clinical endpoints. This proposal utilizes an innovative design and hypotheses to address current NCCAM research funding priorities, by examining clinical efficacy and underlying mechanisms of a promising dietary manipulation with the distinct potential for high impact in terms of ameliorating a chronic, disabling pain disorder.